Delayed thrombectomy in acute stroke effective

R.G. Nogueira, A.P. Jadhav, D.C. Haussen et el published in NEJM on Nov 18,2017 trial results of delayed(6-24 hours) thrombectomy in acute stroke patients who had a mismatch between the severity of the clinical deficit and the infarct volume, conducted at 26 centers in the United States, Canada, Europe, and Australia.

BACKGROUND

National Institute of Neurologic Disorders and Stroke (NINDS) trial was published in 1995 demonstrating a higher likelihood of having a favorable clinical outcome at 3 months when tPA (Alteplase) was administered versus placebo in patients with acute ischemic stroke. Of ischemic strokes, 60% are thrombotic, and 40% are embolic. The brain in ischemic stroke has a core infarct area and ischemic penumbra. The penumbra represents an area that may be salvaged with prompt reperfusion.

However, not all patients have resolution of stroke as even after tPA, residual clot can remain. Endovascular therapies for acute stroke was developed. Several randomized trials showed that endovascular thrombectomy had a clinical benefit when it was performed within 6 hours after the onset of stroke symptoms. There is limited information on the effect of thrombectomy that is performed more than 6 hours after the time that the patient was last known to be well, particularly among patients with ischemic brain tissue that has not yet undergone infarction and may be salvaged with reperfusion.

PATIENT SELECTION

Adult patients with symptoms suggestive of acute stroke and evidence of occlusion of the intracranial internal carotid artery, the first segment of the
middle cerebral artery, or both on computed tomographic (CT) angiography or magnetic resonance angiography.

Patients had to have a mismatch between the severity of the clinical deficit and the infarct volume(Calculated by automated software on CT perfusion scan or diffusion weighted MRI).

They were divided in 3 groups.

Group A were 80 years of age or older, had a score of 10 or higher on the National Institutes of Health Stroke Scale (NIHSS), and had an infarct volume of less than 21 ml;
Group B were younger than 80 years of age, had a score of 10 or higher on the NIHSS, and had an infarct volume of less than 31 ml

Group C were younger than 80 years of age, had a score of 20 or higher on the NIHSS, and had an infarct volume of 31 to less than 51 ml.

TREATMENT

Patients were randomly assigned, in a 1:1 ratio, to thrombectomy plus standard medical care (the thrombectomy group) or to standard medical
care alone (the control group).

RESULTS

Enrollment in the trial was stopped at 31 months, because the results of an interim analysis met the prespecified criterion for trial discontinuation,
which was a predictive probability of superiority of thrombectomy. Total of 206 patients were enrolled in the trial; 107 were randomly assigned to the thrombectomy group and 99 to the control group.

Outcomes for disability were better with thrombectomy plus standard medical care than with standard medical care alone among patients with acute stroke
who received treatment 6 to 24 hours(modified Rankin scale at 90 days was 5.5 in the thrombectomy group as compared with 3.4 in the control group).

Stroke-related death at 90 days, death from any cause at 90 days, and symptomatic intracerebral hemorrhage — did not differ significantly
between the two treatment groups.

 

CURRENT TRENDS IN ACUTE STROKE CARE

Most important factor in acute stroke care is recognition of stroke in community specially by EMS. Most commonly used scale to detect stroke is

Cincinnati pre-hospital stroke scale.

Once patient arrives to Emergency room, most common scale used is NIHSS. This scale, which ranges from 0 to 42, assists in categorizing stroke into “mild” (1–5), “moderate” (6 and 13), and “severe” (>13).

Physician should also be aware of stroke mimics.

Following investigations should be done in a patient with suspected stroke. Electrocardiogram, imaging, complete blood count, basic metabolic panel,
coagulation panel (prothrombin time, partial thromboplastin time, international normalized ratio), and troponin.

Ideal timeline for stroke management is shown in this picture.

CT findings in acute stroke are shown in this table

Once we have a negative CT brain, following criteria are used to provide tPA to suspected stroke patient.  These criteria are recently revised based on current evidence.

tPA can be administered up to 4.5 hours from onset of symptoms. Following are the criteria for that.

Patients who are late then 4.5 hours but less than 6 hours can benefit from endovascular thrombectomy.  Meta analysis of 5 trials is referenced above.

This new trial now gives hope to patients who are late than 6 hours.

One dreaded complication of thrombolytics is intracranial hemorrhage. Following is the classification of intracranial hemorrhage in setting of thrombolysis.

 

Reference

Ischemic Stroke : Advances in Diagnosis and Management Courtney R. Cassella, Andy Jagoda Emerg Med Clin N Am 35 (2017) 911–930

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